1. Field of the Invention
The present invention relates to means for dispensing semi-liquid materials generally and, more particularly, to a novel system for dispensing two such materials simultaneously and in a predetermined ratio.
2. Background Art
There are a number of circumstances in which it is desirable to dispense semi-liquid materials in a predetermined ratio. The materials may include reactive, two component adhesives, sealants, coatings, or potting compounds, in which adhesive one material may comprise a resin compound and the other material a catalyst. The chemical families of such materials include epoxies, acrylics, silicones, polyesters, urethanes, polyurethane foams, and hybrid and reactive elastomers and adhesives.
In some cases, particularly in the past, it was necessary to separately dispense one of two materials and then the other and then to mix them. Various devices have been developed to simultaneously dispense the materials in preselected ratios. These devices generally comprise two cylindrical cartridges, or a single cartridge having two cylindrical bores, for insertion in a cartridge gun which typically has two plungers which move together against seals in one end of the cartridges to dispense the materials from nozzles in the other end of the cartridges. The latter type of cartridge has the disadvantage that the manufacturer must inventory a supply of cartridges for each ratio of materials. Some of the former types provide for the use of different size cartridges, but the cartridges thereof are poorly joined together.
In all known such cartridges, the seals thereof do not provide thorough wiping of the bore of the cartridges and, therefore, the seals may freeze in place, due to hardening of the materials that leak past them, or hazardous materials may be released into the surrounding environment from leakage around the seals. In one prior seal for such cartridges, the seal had a cylindrical body portion, with a convex face which contacted the material in a cartridge. An outwardly facing pointed lip was formed near the end of a portion of the cylindrical shell which inclined outwardly from the shell at an angle of about 6 degrees, forming a trough between the inclined portion the the convex face. As a plunger pressed against the concave inner surface of the face, it tended to flatten the face and thereby forced the inclined portion against the inner surface of the cylinder. While that arrangement was satisfactory for low-pressure applications, the seal tended to leak in high-pressure applications.
Also, in known such cartridges, there is no satisfactory provision for venting air from the cartridges as the seals are inserted therein after filing of the cartridges.
Accordingly, it is a principal object of the present invention to provide a cartridge system for the dispensing of semi-liquid materials in predetermined ratios which system includes two cartridges of selected diameters rigidly fastened together.
Another object of the invention is to provide a seal for a cartridge for dispensing semi-liquid material which seal includes means for ensuring thorough wiping and sealing of the inner surface of the cartridge.
An additional object of the invention is to provide a cartridge for dispensing semi-liquid material which cartridge includes means for venting air from the cartridge as a seal is inserted into the cartridge after filling of the cartridge.
A further object of the invention is to provide a system for dispensing semi-liquid materials in predetermined ratios which system is economically manufactured and has easily changed ratios.
It is another object of the invention to provide means for securely attaching together the two cartridges.
Other objects of the present invention, as well as particular features and advantages thereof, will be elucidated in, or apparent from, the following description and the accompanying drawing figures.